Overview
The EXENT GAM Assay is a sensitive and specific immunoassay that identifies and quantifies M-proteins based on their unique molecular mass. Sample preparation uses paramagnetic beads specific to human IgG, IgA, IgM, total Kappa and total Lambda to isolate immunoglobulins from patient serum. The isolated immunoglobulins are analyzed by MALDI-ToF mass spectrometry to specifically measure the monoclonal protein component. The assay is used in conjunction with the Binding Site Optilite® IgG, IgA and IgM assays to provide semi quantification / reporting in g/L of identified monoclonal proteins.
Each plasma cell produces a unique immunoglobulin
Immunoglobulin molecules consist of two identical heavy chains and two identical light chains (Kappa or Lambda)
When immunoglobulins have their inter-chain disulphide bonds reduced, they are dissociated into their constituent heavy and light chains. The reduced light chains from the intact immunoglobulins are ideally suited to analysis by MALDI-ToF mass spectrometry due to their low molecular weight
The resulting mass spectra reflects the plot of mass vs intensity of the isolated and reduced immunoglobulins
| (A) When immunoglobulins are isolated from the serum of a healthy individual, by specific immunopurification, the resulting MALDI-ToF mass spectrometry resolves three normally distributed peaks that are representative of the polyclonal Lambda, Kappa and heavy Kappa free light chains derived from the intact immunoglobulins.1 |
| (B) In a patient with a monoclonal gammopathy, the presence of a sharp peak within the polyclonal background is indicative of the presence of a monoclonal immunoglobulin. The molecular weight of the identified peak can be used to specifically track the monoclonal protein and the peak area ratio of the monoclonal to polyclonal can be combined with the Optilite IgG, IgA or IgM assay to report a result in g/L. |
When a monoclonal protein is identified, a simple calculation is applied to provide a test result in g/L based on the total immunoglobulin value derived from the Optilite IgG, IgA or IgM assay.
The assay empowers clinicians to effectively diagnose patients with monoclonal gammopathies with a simple serum test. This offers the opportunity to: